Here, the story goes, Oedipus first learned his fate. The Oracle of Delphi, speaking for the god Apollo, told him he would kill his father and marry his mother.

As many of us learn in school, despite all his efforts, Oedipus was unable to escape his disastrous destiny in maybe the most famous of Greek tragedies.

In antiquity, just like today, people had a lot of uncertainties in life and they presumed that the gods knew more than they did, and in particular, they thought Apollo knew a lot. So they would travel here basically to ask Apollo for advice or to ask him questions and hope that he’d give an answer.

If Apollo was a musician, then his priestess, the Pythia, was his instrument. Ancient records tell of mystical, sweet-smelling vapours rising from the earth, putting The Pythia under Apollo’s spell. But while the reciting of prophecies is historical fact, questions about those vapours remain.

Green area on the geological map --Archaeologist John Hale believes the answers lie deep underground. Analysis of the bedrock beneath the temple also shows the existence of petrochemicals, including ethylene.

Ethylene has been used as an aesthetic in modern days, but when administered in experimental small doses, induced a trance-like state. And the trance state had a lot of similarities with the description of the Pythia, there, at the temple of Delphi.

Strollers think water running underground could have carried gases up through the fault lines, directly to the priestess. The Ancients believed ordinary people could meet the gods at Delphi, a point of contact between man and mystery. In a way, they were right. Modern science suggests that, here the supernatural was in fact, simply, natural.